I meet Marlon James in Bloomsbury on the morning of his 45th birthday, as he’s in the middle of a whistle-stop trip to Britain in the wake of this year’s Man Booker prize, which saw his third novel, A Brief History of Seven Killings, romp home to a unanimous victory. Has it been the best birthday year ever? “I can’t complain,” he laughs. “As years go, it’s all downhill from here!” But everything he says gives the lie to his joke: after years patiently waiting for recognition – his debut novel, John Crow’s Devil, was rejected 78 times by American publishers – the only direction for this thrillingly imaginative writer is up.

Triumph in the Booker extended beyond the personal, with James becoming the first Jamaican winner in the prize’s 47-year history; and A Brief History of Seven Killings also animates, through an epic, multi-vocal narrative, a famous moment in recent Jamaican history, the attempted assassination of Bob Marley in 1976. “I like the word first – it means there’ll be more,” he tells me. But, he explains, the reaction in his home country has been “complicated”. James has lived in the US for about a decade, and has taught creative writing and literature at Macalester College in St Paul, Minnesota, for the past eight. His emigration from Jamaica, where he grew up in Portmore, an affluent suburb of Kingston, is intimately connected to his sexuality, an area that he explored in a powerful New York Times essay, From Jamaica to Minnesota to Myself, earlier this year. So while his success was mostly celebrated back home, he explains, making front-page news and getting a mention in the prime minister’s speech, for some it was also a question of “He won, but… ”; while most are happy, “other people are like, oh, the gay dude. And I’m not a writer on a mission, and I’m very suspicious of writers on missions, but I’m also not living a false life. I didn’t bring that issue with me, but it’s an issue that came up, and it makes it complicated.”

And while his identity as a gay Jamaican was discussed in interview after interview, James found himself in the delicate position of “defending the country but not letting it off the hook”. His success, he says, is “something that I think more open-minded Jamaicans can celebrate without hesitation. And I think that open-minded Jamaicans are a far bigger number than people think. I think we have this idea that Jamaica is this den of raging homophobes out to kill everybody in sight, and it’s not true at all. It’s not true at all. Which is not to make light of it – we have some serious issues we need to deal with, and quite frankly, to grow up.” He argues that homophobia in Jamaica is, largely, a hangover from the past: “We like to think it’s religious, but it’s not, it’s Victorian. For one, the law is Victorian, even in the sense that it pretends that lesbians don’t exist; this idea that homosexuality is just buggery. And there is something very colonial in our insistence on keeping it.”

He is adamant that he is not an activist, and has no intention of becoming one, but is nonetheless prepared to speak up when the spotlight falls on him. And he certainly has much to say when it comes to the issue of writers of colour and the expectations that shape notions of what they are “allowed” to write. He recalls a recent panel discussion that also featured Roxane Gay, the American writer of Haitian descent, in which the conversation turned to the kind of questions asked of writers of colour, “especially when we write about violence or atrocity, negative things, things bad that happen, the assumption is either it happened to us, or we know somebody personally who it happened to. The idea that the writer of colour can actually use his imagination just never occurs to anybody.” He himself, he says, is asked whether he grew up in the ghetto and, if not, how he knows what he’s writing about; the answer, he says, is that “you need talent and imagination, like every other writer”.

The prejudice extends to female writers, with similarly limited results: “this assumption that they can only write experiential fiction, [or that] it happened to them, they had a divorce or whatever, it reinforces this narrowing we have of women in fiction”. And yet for writers who are historically regarded as the mainstream, or at the centre of power, it is quite different. As James points out, that writer can situate his work in any setting or period, whether or not it is familiar to him; in short, “a white male writer can write about Vikings”.

The example is not accidental. James’s next novel, which he describes as “my medieval epic”, is set in Africa centuries ago; it is, he says, “a genre book. I’m sure people are going to call it a fantasy novel, which is fine by me.” He is also confident that he’ll return, in future books, to Jamaica in the 1970s and 80s, to what he calls “the interior history of Jamaica”, and that he’ll also examine the Jamaican diaspora. But, he says with a hint of playfulness but clear intent, “I’ve been threatening to write a Viking novel for almost 10 years now.” Gradually, he’s gathering up material, going into the history, immersing himself in Icelandic sagas. You would not bet against it, precisely because James’s path to getting past the novels he thought he should write to find the novels that he really wanted to has been arduous and his success hard-won. As he says, “it’s a weird thing teaching yourself freedom. It sounds so weird, but we actually do have to do it.”